Device for cushioning of compression surfaces

ABSTRACT

A compression device for a mammography unit includes a compression plate positionable in an x-ray field of the mammography unit, and a radiolucent foam pad removably attached to the compression plate that includes an impermeable exposed surface for contacting tissue disposed on the pad within the x-ray field. The pad includes an adhesive layer on the first surface, or a hook and eye fastener for removably attaching the pad to the compression plate. The pad is attached to the compression plate in the x-ray field of the mammography unit, a breast is compressed using the compression plate, a mammogram of the compressed breast is obtained, the pad producing no significant visual artifact on the mammogram, and thereafter the pad is removed.

This application is a Continuation of application Ser. No. 09/620,730,filed Jul. 20, 2000, U.S. Pat. No. 6,577,702 Provisional Data.

This application claims the benefit of Provisional application No.60/187,198 filed Mar. 6, 2000.

BACKGROUND OF THE INVENTION

The present invention relates generally to medical apparatus and methodsand more particularly to devices and methods for cushioning or paddingthe surface of compression plates applied to body parts for purposes ofobtaining x-ray films for example mammography, or other scans ofcompressed tissue.

Currently, in the case of mammography, a patient's breast is placedunder compression by opposing plates attached to a mammography machine.Once under compression an x-ray is taken to determine the presence orabsence of suspect lesions in the breast tissue (e.g. calcifications,tumors). Approximately 25 million screening mammograms are performedyearly, which is estimated to be only a 50% compliance rate amongpotential patients, meaning that number would double if more patientscomplied with the recommended screening regime. One of the more commoncomplaints from mammography patients is discomfort during compression ofthe breast. Most patients can only tolerate up to 10-11 compressionunits. The current legal limit for clinical mammography is 16-18 units.A device which would reduce discomfort could likely improve compliancefor screening.

An important reason for compressing the breast during mammography is toprovide a thinner cross section of tissue for the x-rays to passthrough. When the breast is compressed, it provides optimal imaging ofthe tissue abnormalities with the lowest possible dose of x-rayradiation to the patient. Furthermore, during a mammogram, it isimportant for the x-ray plate to be free from radiopaque material, sothat the diagnostic film, once processed, can give the physician thebest possible picture of the tissue and any abnormalities.

Although patients may tolerate the pain during compression, there is aneed for improved devices and techniques to provide better screeningoutcomes by enabling the use of higher compression force, and byproviding increased patient comfort during mammograms thereby positivelyimpacting patient compliance with mammographic screening and ultimatelyimpacting early detection of cancer and improving patient survival.

Such improved devices must be radiolucent and made of a relativelyhomogeneous material to avoid striations or other variations on theresulting x-ray image, have a low profile to allow for correctpositioning of the breast in the mammography machine, be easily cleanedor disposable for sanitary reasons, and provide structural support andtactile comfort to the patient (both soft to touch and providing a lessharsh or “cold” surface). In addition, such improved devices will permitthe use of higher compression forces to be applied to the breast duringmammograms without the patient reaching her tolerance level fordiscomfort, resulting in a thinner tissue section, better image quality,and reduced x-ray dose to the patient.

It is an objective of the present invention to provide greater patientcomfort thereby increasing screening compliance (e.g. patientwillingness to have more regular mammograms by reducing discomfort ofthe procedure). Greater patient comfort also reduces the risk of patientmovement (voluntary or involuntary). Motion artifact, caused by patientmovement or slippage of the tissue, can result in loss of clarity of themammographic image. It is a further objective of the present inventionto allow for the use of an increased compressive force, for example, upto 16-18 compression units or more thereby providing for a thinnercross-section of breast tissue during the mammogram resulting in anenhanced ability to detect abnormalities in the mammographic image.These objectives are met by the design and use of the present invention.

DESCRIPTION OF THE BACKGROUND ART

Various patents have issued illustrating inventions in the field ofmammography and comfort during x-ray imaging. For example, in the fieldof mammography, U.S. Pat. Nos. 3,963,933, 4,691,333, 4,943,986,5,189,686, 5,553,111 and 5,398,272 describe various fixtures useful forbreast compression. Further, patents have issued describing devices forincreasing comfort during general x-ray procedures, such as U.S. Pat.No. 5,226,070 (radiolucent x-ray mat), U.S. Pat. No. 5,081,657 (buckeywarmer for mammography machine), U.S. Pat. No. 5,541,972 (disposablepadding device for use during mammography) and U.S. Pat. No. 5,185,776(padded cover for x-ray cassette).

SUMMARY OF THE INVENTION

According to the present invention, improved methods and apparatus areprovided for cushioning or providing other patient comfort surfaces ondevices used for compressing the patient's tissue, such as radiographymachines, fluoroscopy units, mammography units and the like. Inparticular a pad element is provided for releasable attachment to atleast one surface of a compression device to be used under x-ray, orother imaging modality.

In a preferred embodiment of the present invention a pad assembly isprovided consisting of a pad element, an adhesive layer and a releasepaper layer allowing for temporary attachment to the applied surface(either the mammography paddle, x-ray plate or directly to the patient'sskin).

An alternative embodiment of the present invention includes a reusablecushioned paddle configured of a self-skinned foam to allow for easycleaning between patients. This embodiment may be replaceable after manyuses or formed integrally wherein the padded surface and the compressionpaddle are assembled as one unit.

The present invention may also incorporate a dispensing unit for accessto single pads for single use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a typical mammography unit having a base and apivoting x-ray unit attached thereto, the x-ray unit including acompression paddle and an x-ray plate.

FIGS. 2A-2B illustrate detailed construction of the x-ray plate and thecompression paddle respectively.

FIGS. 3A-3C illustrate various configurations of compression paddlesutilized during mammography in a standard mammography machine; the shapeand size depending both on the patient's anatomy and the type of x-rayview desired by the physician.

FIGS. 4A-4B illustrate various attachments that can be placed on thex-ray plate to enhance the image, including devices for spot compressionand magnification.

FIG. 5 illustrates a compression paddle and x-ray plate configured foruse in a stereotactic biopsy procedure.

FIGS. 6A illustrates the pad of the present invention having a paddinglayer, an adhesive layer and a release paper layer.

FIG. 6B illustrates another pad of the present invention within a “peelaway” packet.

FIG. 6C illustrates still another pad of the present invention with anadhesive layer and release paper layer just along the border.

FIG. 7 illustrates the installation of the pad of the present inventionon an x-ray plate.

FIG. 8 illustrates the installation of the pad of the present inventionon a compression paddle.

FIG. 9 illustrates various pad configurations and geometries accordingto the present invention depending on the type of compression paddle orx-ray unit used in a given procedure.

FIG. 10A illustrates an alternative embodiment of the present invention,showing the use of a self-skinned foam fastened to a compression paddleintended for use on multiple patients.

FIGS. 10B-10C further illustrate an alternative embodiment of thepresent invention wherein the pad of and compression paddle are integralas one unit.

FIG. 11 illustrates a further feature of the present invention, namely adispensing unit for storing and dispensing the disposable pads of thepresent invention to promote ease of use and efficiency.

FIG. 12 shows a pad assembly on a film holder and compression plate, anda breast being compressed therebetween.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A typical or standard mammography unit used to image the breast whileunder compression is shown in FIG. 1. This unit 10, includes a base 12and a rotating x-ray source 11, comprising an x-ray source 13, a movablecompression paddle 14 and an x-ray plate 15 that holds the film cassette(not shown) as well as serving as a compression surface against whichthe compression paddle 14 can compress tissue e.g. a breast to beimaged. As depicted in FIG. 2A, typically the x-ray plate 15, in certainconfigurations known as a “bucky”, is stationary and includes an opening16 into which an x-ray cassette 17 is placed prior to imaging. The x-rayplate has two patient contact surfaces, a front face 18, and afunctional surface 19. The x-ray plate 15, may optionally includeradiopaque markers 19A at the perimeter of the functional surface 19 toallow various marking schemes to be utilized during a procedure.

FIG. 2B illustrates a more detailed configuration of compression paddle14, including a front patient contact surface 20 and a functionalpatient contact surface 21. Paddle 14 is typically constructed of aclear radiolucent plastic material and is designed to be removablyattached by an interchange assembly 22, to the movable working arm ofthe mammography machine (not shown). These paddles are configured invarious geometries as depicted in FIGS. 3A-3C to accommodate variouspatient anatomies and specific needs of mammographers, such as conedcompression paddles (3A), spot compression paddles (3B) and the axillarypaddle shown as FIG. 3C, all configured to attach to the mammographyunit through standard interchange assembly 22, as shown earlier.

Similarly, the x-ray cassette holder may be adapted by various ancillarymodules such as the spot compression fitting 41 shown in FIG. 4A, and amagnification fitting 42 shown in FIG. 4B. The entire compression system(compression paddle and x-ray plate) can further be modified toaccommodate a stereotactic biopsy procedure as illustrated in FIG. 5. Inthis configuration, compression paddle 14, is modified to include awindow 51, allowing the clinician access to the breast, while stillunder compression, for purposes of placing a device to identify aspecific location in the breast, or to perform an biopsy of tissue.

A preferred embodiment of a pad assembly constructed in accordance withthe present invention is illustrated in FIG. 6A. The pad assembly 60comprises a padding element 61, an adhesive layer 62, and a releasepaper 63 to be removed from contact with the adhesive layer just priorto installation on the surface to be padded. Pad element 61 may beconstructed of various materials having the following characteristics:produce no significant visual artifact on the mammogram (i.e. isradiolucent), be deformable under the forces applied during compressionto provide comfort. Furthermore, the material should provide conformanceto the tissue and the compression surface so as to reduce the propensityfor the material to create air pockets or folds that may be ofsufficient size to be visible on the x-ray image. Additionally, it maybe desirable for the material to be absorptive to external fluids suchas sweat.

Such materials may be an elastomer or gel, open or closed cell foamconsisting of polyolefin, or, preferably a hydrophilic polyurethane opencell foam because of its radiolucent characteristics and soft tactilefeel. The padding material 61 may be a thickness of 0.050″ to 0.500″,preferably in the range of 0.200″ and 0.250″. If an adhesive layer isused, Adhesive layer 62 may be one of a variety of currently availablepressure sensitive adhesives such as acrylic or synthetic rubber basedadhesives, to allow sufficient tackiness for secure attachment to thecompression surface, while also allowing for easy removal (e.g. leavingno detectable residue of adhesive on the applied surface) and disposal.Alternatively, a non-adhesive gel may be used to. secure the pad oranother layer of material having a greater coefficient of frictionagainst the applied surface. It is also anticipated by the scope of thepresent invention, that the pad element may itself be textured such thatit is sufficiently “tacky” to enable its use without an adhesive layer,i.e., by means of friction between the element and the tissue and theunit compression surface.

The pad element of FIG. 6A can be configured with adhesive on the entiresurface of the pad, or at certain regions such as just along the border(see FIG. 6C). FIG. 6B depicts a “peel away” packet configuration tohouse the pad assembly. Optionally, the peel away packet can serve as astiffening element to aid installation of the pad by keeping it in aplanar configuration to minimize the possibility of misapplying the pad(leading to inadvertent air pockets or folds in the material, etc.) andto aid in positioning the pad prior to adhering it to the appliedsurface.

FIG. 7 illustrates, in stepwise fashion, the installation of the padassembly 60 of, the present invention onto the film holder 15. The firststep comprises opening the packing material housing the pad assembly 60(S1), and thereafter removing any release paper 63 therefrom (S2).Installation on the patient contact surfaces of the x-ray plate 15 areshown in steps S3 and S4, S3 showing the placement of the pad element 61on functional surface 19, and optionally extending to front face surface18. Finally, the pad element may be removed and disposed of and thesequence repeated for the next patient. It may be desirable to score orotherwise provide a fold in the pad element at a fixed point from theedge of the pad to accommodate folding the pad onto the front face ofthe applied surface.

A similar sequence of steps (S1 to S4) is illustrated in FIG. 8 showingthe installation of pad assembly 60 of the present invention ontocompression paddle 14. It should be noted that the pad of the presentinvention may be installed on the x-ray plate 15 and the compressionpaddle 14, as shown in FIG. 12, or one and not the other, and furtheroptionally on the front face of either surface depending on the amountof additional cushioning desired. In experimentation with the presentinvention, increased comfort was noted in all of the variousconfigurations as compared to unpadded compression surfaces.

An alternative technique for use of the pad is to attach it to thebreast of the patient instead of on the mammography machine itself. Inthis technique (not shown) the release paper is removed and the adhesiveside of the pad is placed directly on the breast in an area of tissue tobe compressed prior to placing the breast into the mammography machine.

Typical geometries of the present invention are illustrated in FIG. 9,including pad elements for x-ray plate 15 (G1), pad elements withwindows for stereotactic use (G2), spot compression paddles (G3), conedcompression paddles (G4), and axillary paddles (GS).

It is noted that while these configurations reflect the geometries ofvarious commercially available compression paddles and x-ray cassetteholders, the present invention may be manufactured in a wide array ofsizes and shapes. The present invention includes pad assemblies, wherethe pad elements are modular (e.g. using more than one pad to cover adesired surface), or cut to fit the desired surface (oversized with anoverlay pattern to guide the operator in cutting the pad to fit).

An alternative embodiment of the present invention is illustrated inFIGS. 10A-10C. FIG. 10A shows a modular configuration of the presentinvention wherein the pad assembly is constructed from a self skinnedfoam (PA), i.e., foam having an impermeable membrane covering, such as avinyl, deployed over a frame (not shown) and fastened to a compressionpaddle by suction cups, magnets rivets or adhesive (AD) on thenon-functional surface of the compression paddle or x-ray plate. Theself-skinned configuration of the pad assembly allows for washing ordisinfecting and can therefore be applied for multiple patients. FIG.10B illustrates a pad assembly (PA) attached to the paddle on thenon-functional surface by snaps or rivets 110.

FIG. 10C further illustrates an alternative embodiment of the presentinvention wherein the pad 120 of and compression paddle 121 are a singleintegral unit.

FIG. 11 illustrates a dispensing unit according to the present inventionfor housing and dispensing the inventive pad assemblies. Dispensing unit100 includes a housing 101 allowing multiple pad assemblies 103 to bestacked for compact storage, and an access slot 102 for allowing theuser to access one pad assembly at a time.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the present invention.

1. A compression device for a mammography unit, comprising: acompression plate positionable in an x-ray field of the mammographyunit; and a radiolucent foam pad on the compression plate comprising animpermeable exposed surface for contacting tissue disposed on the padwithin the x-ray field, the pad producing no significant visual artifacton a mammogram while in use; wherein the pad and compression plate are asingle integral unit.
 2. The compression device of claim 1, wherein theimpermeable exposed surface comprises an impermeable membrane coveringthe pad.
 3. The compression device of claim 1, wherein the pad comprisesskinned foam.
 4. A method for performing a procedure using a mammographyunit including a compression plate comprising an opening, comprising:providing a cushioning element on a compression surface of thecompression plate in an x-ray field of the mammography unit, thecushioning element comprising an opening therethrough; compressing abreast using the compression plate, the cushioning element deformingunder forces applied during compression to provide comfort; obtaining anx-ray of the compressed breast; and accessing the breast through theopening in the compression plate.
 5. The method of claim 4, wherein thebreast is accessed through the opening to perform a biopsy of tissue ofthe breast.
 6. The method of claim 4, wherein the breast is accessedthrough the opening to place a device to identify a specific location inthe breast.
 7. The method of claim 4, wherein the opening through thecushioning element comprises a window.
 8. The method of claim 4, whereinthe cushioning clement is removably attached to the compression surface,and wherein the method further comprises removing the cushioning elementfrom the compression surface.